Bucky diaphragm



R. F. DENT BUCKY DIAPHRAGM Dec.V 1, 1936.

Filed Dfi. :51, 1954 FIG.Z

ATTORN FIG.. 4fI

for actuating a in extended exposures.

Patented Dec. l, 1936 UNITED sTATEs BUCKY DIAPHRAGM Roy F. Dent, Oak Park, Ill., assignor to General Electric X-Ray Corporation, a, corporation of New York Application December 31, 1934, Serial No. 759,940

2 Claims.

The present invention has to do with X-ray photography or radiography as it is frequently designated, and relates to an improved means bucky diaphragm during its use The primary object of the present invention is the provision of an improved means for moving a bucky diaphragm so that it may be successfully used during extended exposures without producing excessive shadow lines upon a film or plate.

`A secondary object of the invention is the provision of an improved means for moving a bucky grid in a manner which will produce the most ecient results and avoid undesired uneven markings uponV a lm or plate.

A further object of the invention is the provision of novel means for mounting a bucky grid and for moving such grid in its mounting.

`These objects, and such other objects as may hereinafter appear, are obtained by the novel construction, improved arrangement and unique combination of the several elements which constitute the invention, one embodiment of which is illustrated in the accompanying single sheet of drawing, hereby made a part of this specification, and in which:

Figure 1 is a plan view of a device made in accord with the invention and illustrating the motor, cam, and driving parts for the bucky diaphragm;

Figure 2 is a side elevation of the device shown Il Figure 41J Figure 3 is a plan view of the device shown in Figure 1 and taken from the opposite side of the apparatus; and

Figure 4 is an enlarged detail, in a at plane, of a cam track employed Vto impart movement to the bucky diaphragm shown in Figures 1, 2 and 3.

Like reference characters are used to designate similar parts in the drawing and in the following description.

A frame supports the bucky diaphragm and comprises end pieces I0 and I I which are suitably attached to a table, stand or the like (not shown). Between the end pieces IIJ and II is a base or platform I2. The platform I2 supports a motor base I3 on which a motor I4 is mounted.

Extending longitudinally of the base I2 is a reciprocating bar I5. The bar I5 is supported by bearing brackets I6 and I1 suitably mounted on base I2. At each end of the bar I5 are links I8 and I9. Links I8 and I9 are pivotally connected to bar I5 and to bell crank levers 20 and 2l. One end of each of the bell crank levers is pivotally 1 On the sidev of the base I2 opposite to that on Which the linkage just described is mounted are a pair of opposed U-shaped members 2'I and 28 which form tracks for a. cassette 29. The cassette.

29 is removably disposed on said tracks. A/stop 15 29a limits movement in one direction. the form of a latch Means in or lock, not shown, may be against said stop 29a.

The cassette 29 is between the bucky diaphragm 26 and the base I 2. The bucky diais of the'flat of lead and conventional structure for fiat bucky diaphragm. Also mounted upon the diaphragm side of the platform I2 are standards 30, 3l, 32 and 33, having at their endsgrooved roller bearings. The

bucky diaphragm 26 has flanges 34 and 35 which 30 t into the roller bearings to permit of transverse movement of the bucky diaphragm 26 from one side to the other side of the platform. Such rollers maintain the bucky diaphragm 26 in a fixed path at a predetermined distance cassette 29 whether the apparatus is used above a tube, below a tube or in a vertical position at the side of a tube. At each end, the cassette 26 has a stud, 36 and 3'I. On each stud is a hook end of a coil spring, the being marked 3B, and that engaging stud 31 being marked 39. Each spring has a hook at its other end, such other hook end being anchored to a pin or other suitable fastening means 40 and 4I anchored in platform I2. therefore, is always under spring tension, the two springs 38 and 39 urging the diaphragm at all times to one end of its course of movement on the platform. Such tension assists materially in maintaining a uniform cycle of movement for the diaphragm.

The bucky diaphragm is motor driven. The driving mechanism comprises the electric motor I4 suitably connected by a source of energy, -by conduits and a switch,

is connected toa link. `5-' acs from the 35 spring engaging stud 36 4o The bucky diaphragm, 45

(not shown). 'I'he motor 55 diaphragm toward and I4 drives a shaft 42 which is coupled at 43 to a suitably supported worm 44. The worm 44 meshes with a gear 45 upon a shaft 46 having thereon a gear 41, the shaft 46 being suitably mounted for rotation.

The gear 41 meshes with a gear 48 on a shaft 49 also suitably mounted for rotation. The gear 48 is at one end of a shaft 49 and a cam 50 with a peripheral track is at the other end of said shaft 49.

The cam 50 has a peripheral track divided into straight sections 5I and 52 and curved sections or humps 53 and 54. (See Figure 4.)

A pin 55 upon bar I5 rides in the tra'ckfin the face of cam 56, and through the several-gears` described is given alternate reciprocal and-'accelerated movement as the cam 50 is rotated by the motor I4.

The shape of the cam track is such that it produces movement of the pin tion and then in the other direction. The rateV of movement may be constantly changed. vAt the points of direction reversal, the movement of the pin 55 is accelerated. The acceleration is approximately in the ratio of four to one. The bucky diaphragm which moves in a cycle controlled by the pin movements travels transversely of the support I2 at a uniform speed until the end of its path of movement in each directionis approached. At the ends of the path, the speed of the diaphragm is accelerated as indicated and such acceleration extends to the end of the path of movement and for a limited distance over the path of movement in the reverse direction. The bucky diaphragm then travels to adjacent the other end of its path at a selected rate of speed which may be constant or changing. Its speed is accelerated at the other end in the same manner vover the period of the reversal of its movement. Equal portions of the movement of the away `from the end of its path in either direction are accelerated in equal degree.

The `operation of the apparatus is substantially as follows:

A cassette containing a sensitized lm or plate is put in position upon the tracks 21. It may be latched into a fixed position. The motor I4 is then energized. The exposure is then started. An X-ray tube is energized for this purpose. The object to be radiographed is disposed between the tube and bucky diaphragm 26. The length of the exposure generally is a large multiple of the time required for the bucky diaphragm l26 to travel across the base I2 and back again. In fact, the cycle of movement of the bucky diaphragm may be ten seconds and the exposure may be an hour and a half or more. l The present apparatus overcomesthe diiculty which has been encountered from time to time in the taking of X-ray photographs using a bucky diaphragm. Bucky diaphragms have been made to move transversely of tables and other supports. The speed has been regulated by a dashpot or by a mechanical means when the bucky was moved from one side to the other only. When it was necessary to move the bucky diaphragm from one side to the other side before the exposure was complete heavy shadow lines developed on the photograp Numerous efforts have been made to obtain pictures using a bucky diaphragm` and withoutl objectionable vshadow lines.

Continuous diaphragms have been rsuggested but these are bulky, diicult to handle, and gen- 55 first in one direc- I erally get out of order because it is necessary to make such diaphragms with relatively movable parts. All previous efforts to take satisfactory pictures with a reciprocating diaphragm have been more or less unsuccessful in that undesirable shadow lines have developed on the photograph parallel to the lead strips within the diaphragm. These lines were produced incident to the changes in the-course of the diaphragm, thatl is, the undesirable shadow lines resulted from the diaphragm coming to a stop as it reversed its movement.

It has been discovered by the applicant that by accelerating the speed of the diaphragm at the end of its strokes in either direction and continuing such. acceleration during the initial por- -tion of the return movement of the diaphragm and by establishing a ratio between the periods of `acceleration and the periods of normal movement, he can overcome the difficulty of photographing undesirable lines upon the radiograph and the distorting lines heretofore developed and found objectionable are not found in negatives produced with the present apparatus.`

From experiment and actual operation, it'has been found that highly satisfactory results are obtained when the proportion of the movement of the diaphragm that is accelerated is about onesixh or one-seventh of the total travel of the diaphragm, and the degree of acceleration is about four times the diaphragm. The period of complete stoppageo'f the diaphragm under these circumstances is quite brief if a complete cycle of movement of the diaphragm in both directions requires ten seconds. Care, of course, must be exercised not to havethe movements of the diaphragm 26 in synchronism with the energization of the X-ray tube, such energizationbeing timed by the impulses of current impressed thereon. In half wave rectification of sixty cycle current, these impulses are sixty to the normal movement of the d second and in full wave one hundred and twenty phragm by reversing the apparatus in a horizonc tal plane or by moving the apparatus into a vertical plane. The operation of the device is substantially the same in any of these positions because of the spring tension under which the diaphragm is maintained at all times. overcome by the motor in each position, for operative purposes, is substantially the same.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. In combination, a support frame, a radiographicl diaphragm mounted for reciprocating sliding movement on said frame, a `cylindrical drum journalled on said frame, means on said frame for rotating the drumat substantially uniform angular velocity, tinuous slot formed in the cylindrical surface thereof, said slot comprising complementary substantially helical portions extending oppositely in said drum from a point spaced from one end thereof to a point spaced of the drum, said slot at the intersection of said complementary helical portions defining salients extending each toward the adjacent end of the drum, cam following means supported on said frame and extending in said slot and drivingly connected with said diaphragm to reciprocate the same in response to rotation of said drum.

2. In combination, a support frame, a radiographic Adiaphragm mounted for reciprocating The inertia v to be from the opposite end sliding movement on s-aid frame, a cylindrical slidable on the frame in a direction substantially drum journalled on said frame, means on said parallel with respect to the aXis of said drum, said frame for rotating the drum at substantially unimember having a cam following projection eX- form angular velocity, said drinn having a contending in said slot and bellcrank means tiltable tinuous slot formed in the cylindrical surface on said frame and having a portion connected to thereof, Said Slot Comprising complementary said member and another portion drivingiy consubsta-ntially helical portions eXtenoling oppositenected with said diaphragm whereby reciprocatly in Said drum flOm a point Spaced from one end ing movement imparted in said member by the thereof t0 2 DOH spaced flOm the Opposite end turning of said drum may cause reciprocation of of the drum, said slot at the intersection of said Said diaphragm in e, direction intersecting the complementary helical portions dening saliente direction of reciprocating movement of said memextending each toward the adjacent end of the ber, drum, cam following means supported on said ROY F. DENT. frame and comprising a member longitudinally 

